Method for treating welds



July 27, 1943- R. CRAIG METHOD FOR TREATING WELDS Filed Jan. 23, 1940 v1! u m m m M n n W m s m m J gagaag n m agfi J5 J a w w M a w w M 5 G NWM m 4 B 95 a z a a E #1 \M\\\\\|H m 8 U 4 8 J 4 m RM m WR NS E mATTORNEY Patented July 27, 1943 2,325,113 sm'rnop Foa TREATING wnnns'James B. Craig, Kenmore, N. Y., assignor to The Linde Air ProductsCompany, a corporation of Ohio Application January 23, 1940, Serial No.315,195

'1 Claims. (01. 148-211 This invention relates to the fabrication of oilwell casing and similar structures comprising a series of metal pipes orsimilar sections welded end to end. More particularly, the inventionrelates to a method for treating welded joints or other welds,especially those in iron and steel. A principal purpose of the inventionis to produce in such welded joints, in a minimum time, an improvedmetallographic structure. The invention is advantageously applied towelds immediately after the welding operation and before the temperatureof the weld metal has fallen below the critical range. In such cases thetime required for the cooling step is decreased and the overall time forthe complete welding cycle is shortened. In case it is impossible tocarry out the treatment before the temperature of the weld metal hasfallen below the critical range. the weld may be reheated to atemperature at least above the lower critical point.

In the welding of oil well casings, the first section of pipe or casingis lowered into the drill or well hole, and held in vertical position.The next section is then clamped in .end-to-end relation with the iirstsection, and the two sections are tack welded to prevent misalignment ordistortion due to the welding heat or other causes. The adjoiningsections are then butt welded, as by fusion depositing filler materialalong and lietween the opposed ends while so secured together, thusinsuring good penetration of the weld iiller material. Prior to thepresent invention, the sections were maintained in their position untilthe weld or seam had cooled enough to have a tensile strength sumcientto support the casing below it, whichuptothenhad beenheldbyaclamp. Thisclamp was then released and the fabricated casing was lowered and thesesteps were repeated until the casing had reached the desired length.

Whentheweldseaminanoilwellcasingis allowed to cool by dissipation ofheat to the surrounding atmosphere and to remote portions of the casing,the cooling period may be as high as to minutes. Since it is necessaryto wait until the weld seam has cooled before subjecting it to anysubstantial tensile stress, attempts have been made to cool the weldseams by employing various rapidly moving liquid cooling media, such aswater or oil, applied directly against both the seam and to the portionof the sections immediately adjacent thereto. However, such cooling, iitoo rapid, may cause brittleness at the weld seam. Furthermore, there isa probability of intense internal stresses which are undesirablecharacteristics in any we ded assembly. and especially so in oil wellcasings, where the assembly is subjected to repeated shocks during theinstallation and where any failure leads to an expensive "flshin8 opThese internal at are due among othercauseatothefactthatwhentheendoiaweld joins the beginning or a weld thereare produced so-called hot spots or portions of higher than ordinarytemperature. Such hot spots are produced by the circumferential weldingof any cylindrical pipe unless the diameter of the pipe issogreatthattheportlonoithepipewherethe weld was started has had time tocool bei'orc the completion of the weld reaches this beginning.Suchisnotthecaseintheweldingoi'oilwell casings of the sizes commonlyused. In fact, for thesake oispeeditiscustomarytohavetwo welders startat diametrically opposite points, and thus two hot spots are produced.1i substantial differences in temperature about the P iph ry of the weldare not eliminated before any portionof the metalin theweldsonecoolshelowthe critical range, severe internal stresses will beset up.

In iabricating oil well casing by welding it is desirabletoreducethetimerequiredi'orthecooling steps of the entire welding cycle.The temperature of the weld at the finish of the cooling operation mustbe low enough that the weld will have suiilcient strength to support the"string" or assembled casingdepending from it. The time of the entirewelding operation, including the coolingstenmustnotbegreatlyinexcessoithat required for the making or screw-threaded connections. Themetallographic structure of the weld should be satisfactory.

The selection of a suitable quenching medium to prevent internalstresses and to secure sood metallographic structure, and the correctemployment of this medium therefore are of anportance. Suitable mediaare fluids such as waterorair whenusedunderparticularconditions and inconnection with a novel apparatus which is to be described herein andwhich forms part of the present invention.

One of the principal objects of this invention is to provide a simpleand economicaLprocess whereby the weld, seam or joint, joiningfabricated parts, may be cooled-quickly while avoiding brittlenesstherein. Another object is to provide aprocessoicoolingrapidlyandatthesame time preserving resistance to shocks in theseams. Still another object of this invention is to provide a method ofdecreasing the brittleness of welded seams which have been allowed tocool at a rate which. fails to give the best metallographic structure. Afurther object is to eliminate substantial differences in temperature indeposited meld metal and in the metal adjacent the weld. Yet anotherobject of this invention is the production of a metal construction orassembly such as a pipe or casing having a weld seam which is lacking inbrittleness and is unusually tough and strong.

Other objects of the invention will in part be set forthhereafter-andwillinpartbeevident from the following description taken inconnecand pulled against the force of the spring 22.'

tion with the accompanying drawing in which: On the semi-cylindricalmember which does not Fig. 1 is a view in front elevation ofapparasupport spring clamp means IS, in the present tus suitable for usein the practice of the inven case member 8, there is provided a pair oflugs tion in use on an oil well casing, the drawing or other projections84. These lugs are furshowing the casing cooled to a temperature atnished with concavities or notches 82 with which which the apparatuswould normally be rethe lugs 38 interflt to clamp the device in placemoved; on the casing. with this arrangement, the grip Fig. 2 is avertical sectional view of the ap- G of the handle 28 may be pulledagainst the paratus taken on the plane of line 2-2 of Fig. 1; force ofthe spring 22 to latch and release the and spring clamp it with one handwhile the other Fig. 3 is a horizontal sectional view taken on hand isused properly to position the device B on the plane of line 8-4 ofFig. 1. the casing C relative to the weld seam S. It will Certain of theobjects above-defined are be noted that upon application of the device Bachieved by the provision of a method of proto the heated casing thespring 22 is under congressively fabricating an oil well casing as it issiderable compression; as the weld cools and lowered into a well.According to the invention, the members 8 and 8 approach each other thea metal casing section is supported in position spring 22 expands butnot to such an extent to be lowered into the well, and another sectionthat the rod 24 engages with the inner end of is aligned in end-to-endrelation with the first the bore l8. section. The sections are thenwelded together, In order that the members 8 and 8 may be for example byoxyacetylene methods. While spaced from the weld seam S, thesemi-cylinthe metal 01' the welded joint is still at a temdrical members8 and 9 are provided with perature above its critical range, the jointand g oo es e e grooves are aligned d o m adjacent areas are covered,preferably by a de- 25 a practically continuous annular groove when vicelater to be described, and a cooling fluid the device B is assembledabout a casing. Thus, such as water or air is directed at the lowercasthe clamp l8 acts to maintain the members 8 and ing section .at apoint below, but close to, the 8 in physical contact with the pipe orcasing C as weld until the metal at the joint is cooled below the lattercontracts in cooling with the device its critical range. The joint isthen uncovered 3 covering substantially all of, but bein O t Di and theunited sections lowered" into the well ntact with. the weld seam S. fora distance about equal to the length of a At the top of each of thesemi-cylindrical single section. The process is then repeated, 1,.members 3 and 9 there 18 Prflvided an p adding new sections, until thedesired length of xtending skirt comprising semi-cylindrical casing iproduced, parts 42 and 43, welded or otherwise secured to In connectionwith the described method, ap-L, the upper edge of the members 8 and 9respecparatus of the type illustrated in the accom tively. It has beenfound that brass is a parpanying drawing may be used. In the drawingticularly suitable material for these skirt memthere is shown by way ofexample a cooling bers, although the invention is in no way limited viceapplied to an oil well casing C. This casinggf in to such a material.The skirt members 42 and consists of an upper casing section U and alower. .44 have front edge flanges to Prevent te casing section L, thetwo sections being e n-w ,Tdrom entering the crack between them. Thenected together by a circumferential weld joint 7 (V ir formed by thesemembers preven y i or seam s. The cooling device or block B come; thecooling medium. s as w when pplied prises a pair of semi-cylindricalmembers 8 and 4; in a manner hereinafter set forth. from p 8, preferablyconsisting of metal having a high. 8 p Over the miylindrical members 8and thermal conductivity, such, for example, as cop- -L and running wnthe r e of he upper per. The semi-cylindrical members 8 and 9 section Uof the easing into the weld seam S.

connected together as by a hinge H for open It has been found that whenusing the device and closing movement over the casing C; At th Water canbe p y d s cooling medium. d of th d i opposit t hinge there 15' Thewater or other cooling medium is directedby provided spring clamp meansl8, preferably hose or pipes 48 and 41 in streams 48 and 48. comprisingan arm l2 pivoted at l4 toa lug l8 on V e Streams 48 nd 49 sho i pi onhe one of the semi-cylindrica1 members, For conlower casing L ate ybelow t -cy v me th spring damp means I; has been drical members 8 and8. Heat isconduoted from hown on th mn m member 1 The the weld or seam8, through the lower casing arm is provided with a bore 18 enclosed byan to the P in W ere the streams 48 and 48 imapertured cap 28 which issecured to the arm I: plnge upon it. Scme of the heat is of course by asuitable means such as screw threads. eondllcted illated t0 the members8 and 8 Within the bore and extending thro h the pand it is desirable toprevent them from overerture in the cap is a rod 24 carrying a thrusthcating- However. it has been ou d t fltthe washer 28 at the end remotefrom the cap. A splashing which occurs when streams of waterare coiledcompression spring 22 surrounds the rod directed with some force on thecas n mmed 24 engaging the thrust washer 28 and the cap ately below thesemi-cylindrical members, and 28 to urge the rod-24 in a left handdirection, an occasional direct impingement of the streams as seen inthe drawing. Any other means for generally serves to prevent the membersI and 8 holding the rod 24 may be employed, bearing in v fromoverheating. mind the necessity of giving a certain amount of In the useof this apparatus it is preferred play to the rod and hence to the twosemi-cythat when attaching the block or cooling device lindrical membersto compensate for shrinkage 7 B to the casing that the center of each ofthe during cooling of the work. ortions 8 and 8 preferably be locatedover the Secured to the end 01 the rod 24 is a handle points where thefinish of one weld overlaps the 28 having a pair of lugs 88 thereon fora purpose beginning of the other weld and hence at the to be disclosedhereafter. The handle is also hottest point. The streams of water 48 and48 provided with a grip G so that it may be grasped 7i; preferably aredirected onto the lower section L of the casing C just below the blockof points vertically below the hottest points of the weld or seam S.Thus the weld first tends to reach a uniform temperature and then iscooled further to a point sufficiently below the critical temperature,which in the case of the medium carbon steel casing ordinarily employedis about 1000 F.

As has been stated the pipe or casing C contracts and the sections 8 and9 gradually approach each other under the influence oi the spring 22.When the weld or seam S has cooled sufllciently the block B is removedby gripping the handle G so that the lugs 39 move out of the notches 82.Thus, the spring clamp means II can be moved bodily away from the armsor projections 34 on the member 9 and the two halves of the block swungabout the hinge H and the block removed from the casing 0. Water may bethen directed onto the weld for a few seconds until the temperature hasbeen lowered to about 150 to 250 F. The metal will then have sufficienttensile strength to withstand the weight of the casing when the casingis lowered, being held entirely by the upper section U. The upper casingsection II forms then the lower section of the next weld to be assembledand the process is repeated. f

It will be evident that this method of cooling the weld gives the speedwhich is required in the field and furthermore it has been found that.notwithstanding the shortness of the time involved, internal stressesand excessive brittleness of the weld seam are eliminated. In fact, ithas been found that the metallographic structure, freedom frombrittleness, and the strength, are superior to those obtained when theweld is allowed to cool by radiation or conduction to normal atmosphereor both.

While the size of the apparatus may be varied within wide limits, it hasbeen found that for a pipe having an outside diameter 01' 5% inches, anapparatus consisting of two assembled copper members with an insidediameter of 51'; inches and a thickness cl 1 inch tapering down to A;inch 2 inches away from the weld on each side of the weld, grooved tofit about the weld, is satisfactory. For larger pipe, the insidediameter of assembled copper blocks is made inch larger than the outsidediameter of the pipe, the width and thickness remaining the same. Thedevice is so proportioned that when the pipe has cooled to about 1000 F,the device will iit snugly aroimd the pipe or casing. The skirt ispreferably about 12 inches high. Using a block or device 01' this size,the we'd is cooled to a temperature at which it is black in color indaylight in about one and one-half minutes, and the weld is then furtherchilled with water for a few seconds after the removal of the block.

Some or the advantages heretofore described. 1. e. the improvedmetallographic structure, may beobtainedeveninacasewhereaweldhasbeencooled from welding temperature at a rate which falls to givethe optimummetallographic structure. This is done by heating the weld to atemperature at least above the lower critical temperature and thencooling it at a rate, and by the methods, heretofore described. Theadvantages of improved metallographic structure are secured but 01'course no saving in time results.

The use of the device described and illustrated in the drawing forcovering a newly-made weld is beneficial in that it aids in preventingoxidation of the weld, protecting it from undue access of air. Whenwater is used as the cooling fluid in conjunction with such device, itflows down the outside of the lower casing section, assisting in coolingit.

While various detailed embodiments have been illustrated in the drawingand described in the accompanying specification, obvious modificationswill be readily apparent to those skilled in the art.

I claim:

1. A method of cooling a newly welded metal Joint between metal memberswhich comprises directing one or more streams of cooling fluid againstone of said members adjacent to, but not directly against, such joint,while said joint is temporarily covered to exclude such cooling fluidfrom direct contact therewith.

2. A method or coolin a newly welded metal joint between metal memberswhich comprises directing a cooling liquid against one of said membersadjacent to such joint, while said joint is temporarily covered by aheat-conducting protective device to exclude such liquid from directcontact with said ioint, said cooling liquid being so directed that someof such liquid splashes against said protective device to cool thelatter.

3. A method of cooling a newly welded joint in a member such as a metalpipe or casing which comprises surrolmding said joint while hot with aprotective device of heat conducting material and directing coolingfluid against said member closely adjacent to said protective device.

4. A method of quickly cooling a newly formed circumferential weld seambetween metal pipe sections or the like which comprises maintaining thepipe sections in a vertical position, surrounding the hot seam with aprotective device, and directing a cooling fluid against the pipe belowthe protective device.

5. Aprocessot quicklycoolingahotweldseam inapipeorthelikewhichcompriscscovering the weld seam and closely adjacentarea with an annular metal member spaced from but protecting said weldseam before the metal of the weld seam has cooled below the criticaltemperature and applying a fluid cooling medium to said pipe close tosaid metal member until said metal is cooled below its criticaltemperature.

6. A method as set forth in claim 5 which includes the additional stepsof removing the metal member alter the metal at said seam has cooledbelow its critical temperature and then directing the cooling fluiddirectly against said weld seam.

7. A process of cooling a hot horizontal weld scam in a vertical casingwhich comprises the steps of applying a protective heat conductingdevice to the hot points or the weld seam and ad- ,iacent areas 01 thecasing before the metal or such weld has cooled below its criticalrange. directing a liquid cooling medium against uncovered areas of thecasing immediately below saidprotectivedeviceandinwith said hotpolntsunnlthemetaloitheweldseamis cooled below the critical range,-removing said protectivedeviceiromthecasinmanddirecflni l0aiiuidcoolingmediumagainsttheexposedweld seam.

JAMES a. cane.

, CERTIFICATE; OF CORRECTION. Patent no. 2,52 ,115. July 27, 191

JAMES R. CRAIG.

It is hereby certified that error 'appears in the printed specificationof the above numbered patent requiring correction as follows: Page .1,second column, line 55, formeld" read we1d--; pege}, second column, line65, claim 7, after weld' insert --sea:n--; and that the said LettersPatent should be read with. this correction therein that the same mayconform to the record or the cage in the Patent Office.

si ned and sealed this 7th da'y f September, A. 1). 1915.

or Henry Van Ar'sd aley (Seal) Acting Commissioner of Patents.

